Camshaft phaser

Abstract

An internal combustion includes a crankshaft and a camshaft rotatable by the crankshaft. The internal combustion engine also includes an oil source, an engine cover, and a drive member disposed within the engine cover for transferring rotational motion from the crankshaft to the camshaft. A camshaft phaser actuated by an electric motor is disposed within the engine cover for controllably varying the phase relationship between the crankshaft and the camshaft. A supply passage communicates oil from the oil source to the camshaft phaser in order to lubricate the camshaft phaser and a drain passage drains oil from the camshaft phaser to the oil source. A sealing arrangement defines a dry zone within the engine cover to isolate the drive member from oil used to lubricate the camshaft phaser.

We claim: 
     
       1. An internal combustion engine having a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by the crankshaft about a camshaft axis, said internal combustion engine comprising:
 a) an oil source; 
 b) an engine cover; 
 c) a drive member disposed within said engine cover for transferring rotational motion from said crankshaft to said camshaft; 
 d) a camshaft phaser disposed within said engine cover for controllably varying the phase relationship between said crankshaft and said camshaft, said camshaft phaser comprising:
 i) an input member driven by said drive member; 
 ii) an output member rotatable with said camshaft; 
 iii) a gear drive unit connecting said input member to said output member; and 
 iv) an electric motor connected to said gear drive unit to impart rotation on said gear drive unit such that rotation of said gear drive unit causes relative rotation between said input member and said output member; 
 
 e) a supply passage for communicating oil, in use, from said oil source to said camshaft phaser in order to lubricate said camshaft phaser; 
 f) a drain passage for draining oil, in use, from said camshaft phaser to said oil source; and 
 g) a sealing arrangement defining a dry zone within said engine cover to isolate said drive member from oil used to lubricate said camshaft phaser. 
 
     
     
       2. An internal combustion engine as in  claim 1  wherein:
 said input member is a housing having a housing bore with a longitudinal axis; 
 said gear drive unit is a harmonic gear drive unit disposed within said housing, said harmonic gear drive unit comprising a circular spline and an axially adjacent dynamic spline, a flexspline disposed within said circular spline and said dynamic spline, a wave generator disposed within said flexspline, wherein one of said circular spline and said dynamic spline is fixed to said housing in order to prevent relative rotation therebetween; 
 said output member is an output hub rotatably disposed within said housing axially adjacent to said harmonic gear drive unit and attached to said camshaft and fixed to the other of said circular spline and said dynamic spline in order to prevent relative rotation therebetween; and 
 said electric motor is connected to said wave generator to impart rotation on said wave generator such that rotation of said wave generator causes relative rotation between said circular spline and said dynamic spline. 
 
     
     
       3. An internal combustion engine as in  claim 2  wherein said sealing arrangement comprises an engine cover to camshaft phaser seal to seal between said engine cover and said housing. 
     
     
       4. An internal combustion engine as in  claim 3  wherein said engine cover to camshaft phaser seal is a radial seal. 
     
     
       5. An internal combustion engine as in  claim 3  wherein said housing rotates relative to said engine cover to camshaft phaser seal. 
     
     
       6. An internal combustion engine as in  claim 3  wherein said engine cover includes a ring-shaped engine cover seal support extending axially from said engine cover toward said camshaft phaser and said engine cover to camshaft phaser seal is located within said engine cover seal support. 
     
     
       7. An internal combustion engine as in  claim 6  wherein said housing includes a ring-shaped housing sealing body extending axially from said housing toward said engine cover such that said engine cover to camshaft phaser seal seals against said housing sealing body. 
     
     
       8. An internal combustion engine as in  claim 3  wherein:
 said camshaft phaser further comprises a back plate at one end of said housing, said back plate including back plate central bore extending axially therethrough; 
 said internal combustion engine further comprises a camshaft support which supports said camshaft; and 
 said sealing arrangement further comprises an engine to camshaft phaser seal to seal between said back plate and said camshaft support. 
 
     
     
       9. An internal combustion engine as in  claim 8  wherein said engine to camshaft phaser seal is a radial seal. 
     
     
       10. An internal combustion engine as in  claim 8  wherein said back plate rotates relative to said camshaft support. 
     
     
       11. An internal combustion engine as in  claim 8  wherein said camshaft support defines a camshaft support bore and said engine to camshaft phaser seal is located within said camshaft support bore. 
     
     
       12. An internal combustion engine as in  claim 11  wherein said back plate includes a ring-shaped back plate sealing body extending axially from said back plate into said camshaft support bore such that said engine to camshaft phaser seal seals against said back plate sealing body. 
     
     
       13. An internal combustion engine as in  claim 8  wherein said sealing arrangement further comprises a back plate to housing seal to seal between said back plate and said housing. 
     
     
       14. An internal combustion engine as in  claim 13  wherein said back plate to housing seal is located radially between said housing bore and said back plate. 
     
     
       15. An internal combustion engine as in  claim 14  wherein said back plate includes a back plate groove on the outer circumference thereof and said back plate to housing seal is located within said back plate groove. 
     
     
       16. An internal combustion engine as in  claim 8  wherein said sealing arrangement further comprises an engine cover to motor seal for sealing between said engine cover and said electric motor. 
     
     
       17. An internal combustion engine as in  claim 1  wherein said sealing arrangement comprises an engine cover to camshaft phaser seal to seal between said engine cover and said camshaft phaser. 
     
     
       18. An internal combustion engine as in  claim 17  wherein said engine cover to camshaft phaser seal is a radial seal. 
     
     
       19. An internal combustion engine as in  claim 17  wherein said camshaft phaser rotates relative to said engine cover to camshaft phaser seal. 
     
     
       20. An internal combustion engine as in  claim 17  wherein said engine cover includes a ring-shaped engine cover seal support extending axially from said engine cover toward said camshaft phaser and said engine cover to camshaft phaser seal is located within said engine cover seal support. 
     
     
       21. An internal combustion engine as in  claim 20  wherein said camshaft phaser includes a ring-shaped sealing body extending axially from said camshaft phaser toward said engine cover such that said engine cover to camshaft phaser seal seals against said sealing body. 
     
     
       22. An internal combustion engine as in  claim 17  wherein:
 said camshaft phaser further comprises a back plate at one end of said camshaft phaser, said back plate including back plate central bore extending axially therethrough; 
 said internal combustion engine further comprises a camshaft support which supports said camshaft; and 
 said sealing arrangement further comprises an engine to camshaft phaser seal to seal between said back plate and said camshaft support. 
 
     
     
       23. An internal combustion engine as in  claim 22  wherein said engine to camshaft phaser seal is a radial seal. 
     
     
       24. An internal combustion engine as in  claim 22  wherein said back plate rotates relative to said camshaft support. 
     
     
       25. An internal combustion engine as in  claim 22  wherein said camshaft support defines a camshaft support bore and said engine to camshaft phaser seal is located within said camshaft support bore. 
     
     
       26. An internal combustion engine as in  claim 25  wherein said back plate includes a ring-shaped back plate sealing body extending axially from said back plate into said camshaft support bore such that said engine to camshaft phaser seal seals against said back plate sealing body. 
     
     
       27. An internal combustion engine having a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by said crankshaft about a camshaft axis, said internal combustion engine comprising:
 a) an oil source; 
 b) an engine cover; 
 c) a drive member disposed within said engine cover for transferring rotational motion from said crankshaft to said camshaft; 
 d) a camshaft phaser disposed within said engine cover for controllably varying the phase relationship between said crankshaft and said camshaft, said camshaft phaser comprising:
 i) a housing having a housing bore with a longitudinal axis; 
 ii) a harmonic gear drive unit disposed within said housing, said harmonic gear drive unit comprising a circular spline and an axially adjacent dynamic spline, a flexspline disposed within said circular spline and said dynamic spline, a wave generator disposed within said flexspline, wherein one of said circular spline and said dynamic spline is fixed to said housing in order to prevent relative rotation therebetween; 
 iii) an output hub rotatably disposed within said housing axially adjacent to said harmonic gear drive unit and attached to said camshaft and fixed to the other of said circular spline and said dynamic spline in order to prevent relative rotation therebetween; and 
 iv) an electric motor connected to said wave generator to impart rotation on said wave generator such that rotation of said wave generator causes relative rotation between said circular spline and said dynamic spline; 
 
 e) a supply passage for communicating oil, in use, from said oil source to said camshaft phaser in order to lubricate said camshaft phaser; 
 f) a drain passage for draining oil, in use, from said camshaft phaser to said oil source; and 
 g) a sealing arrangement defining a dry zone within said engine cover to isolate said drive member from oil used to lubricate said camshaft phaser.